add option factor
remove pry
comments and another spec
pry :)
improve spec
Merge pull request #1 from schasse/factored_sampling

Factored sampling
follow up
Merge pull request #2 from schasse/factored_sampling

factored sampling follow up
version bump to 0.2.0: scale weights by optional factor
add spec and bigdecimal fix
big factors have lower impact now
Merge pull request #3 from schasse/float_issue_fix

bigdecimal fix and spec